Field of Invention
The present invention relates generally to containment vessels and more particularly to a movable reusable frame-like structure to surround and support a flexible bladder type fluid containment vessel for use in hydraulic fracturing operations.
Background
Induced hydraulic fracturing or hydro-fracturing, commonly known as “fracking”, is a technique in which water is mixed with sand and chemicals, and the mixture (fracturing fluid) is injected at high-pressure into a well bore to create small fractures (typically less than 1 mm), along which desirable fluids including gas, petroleum and hydrocarbons may migrate to the well for collection and harvesting.
The hydraulic fractures are created by pumping the fracturing fluid into the well bore at a rate sufficient to increase down hole pressure above the fracture gradient (pressure gradient) of the rock. The rock cracks and the fracturing fluid continues propagating into the rock, extending the crack still further. Introducing a proppant, such as grains of sand, ceramic, or other particulates, into the fracturing fluid prevents the fractures from closing upon themselves when the pressure of the fracturing fluid is removed.
Hydraulic fracturing equipment usually consists of a slurry blender and one or more high-pressure high-volume fracturing pumps, a monitoring unit and associated equipment including fracturing fluid tanks, vessels for the storage and handling of proppant, a variety of testing, metering and flow rate equipment and storage tanks and/or ponds for fresh water and waste water. Typically, fracturing equipment operates in high-pressure ranges up to 15,000 psi and at high volume rates of 9.4 ft.3 per second (approximately 100 barrels of fluid per minute). Because of the high volume of fluids and water used in the fracking process, it is necessary that large volumes of water be readily available for injection into the well, and also that the well site have facilities for capturing and storing and perhaps recycling the waste water ejected from the well.
The fluid injected into the well is typically a slurry of water, proppants, and chemical additives comprising approximately 90% water, about 9.5% sand and approximately 0.5% chemical additives. The typical fracturing treatment uses between 3 and 12 chemical additives which may include: acids, sodium chloride, poly acrylamide, ethylene glycol sodium carbonate, potassium carbonate, flutaraldehyde, guar gum, citric acid and isopropanol.
The fracking process produces “wastewater,” also known as “flow back water” or “produced water” which is returned to the surface during the fracturing process and after the fracking process is completed. The fracking process typically requires between two and five million gallons of freshwater (also called “sweet water”) per well. Approximately 10%-40% of the fluid that is pumped into the well returns to the surface as wastewater which may contain a variety of contaminants including hydrocarbons, carbon dioxide, hydrogen sulphide, nitrogen, helium, harmful elements such as mercury, arsenic, and lead, particulates, chemicals and salts. Wastewater production commonly averages between 3,000 barrels and 5,000 barrels per day at 42 gallons per barrel. (126,000-210,000 gallons).
During fracking operations, the fresh water (sweet water) is typically held in tank trucks or plastic lined ponds/depressions dug into the ground proximate the well, and plumbing apparatus is used to withdraw the fresh water from the tanks/ponds and supply it to blenders or other apparatus for adding proppants and chemicals prior to the slurry being pumped to the well head for high pressure injection down the well.
Following the injection of the slurry into the well, the wastewater exits out the well bore and is typically pumped into wastewater storage tanks or into wastewater ponds that are lined with plastic, or the like, to prevent the wastewater from leaching into the ground. After fracking is complete, the wastewater storage tanks and/or wastewater storage ponds are drained and the waste water is transported to salt water dumps (SWDs) or hazardous water sites for permanent disposal.
In the Marcellus Shale deposit it is estimated to cost more than $3 per barrel to dispose the wastewater and $7 to $10/per barrel to transport wastewater to a disposal site. There is also a cost for fresh water needed for fracking. In drought areas, fresh water is a large cost factor. For example a horizontal well may use approximately 4.2 million gallons of fresh water.
Fresh water sourcing is becoming a revenue business as some municipalities and landowners in the western US are selling water rights to the drilling industry for fracking.
It is estimated in the near future, fracking operators may have to pay as much as $6,000.00 for a disposal charge per tank load excluding the transporting cost of getting the wastewater to the dump site.
There are four primary methods for dealing with the wastewater, and all four primary methods require a means/apparatus for storing and/or containing the water. A first method reuses the wastewater in the fracking process. Unfortunately, reuse is problematic as high levels of contaminants may plug the well with “residual chemicals”, particulates, or “shale fines” which may negatively impact production of the well.
A second method is “deep well injection,” which entails drilling a deep disposal well into which the wastewater is pumped for permanent disposal. However, this option too is problematic, as seismologists and the scientific community have alleged earthquakes “were almost certainly induced by the disposal of fracking wastewater in deep disposal wells.” The drilling of a disposal well is also expensive.
A third method is on-site treatment of the wastewater which is designed to remove the most harmful chemicals and byproducts from the wastewater. The treated water may then be reused in fracking. On-site treatment generally has negligible transportation costs, but may be more expensive than other treatment options due to the necessary equipment and facilities for treatment and the need for space to accommodate the treatment equipment.
The fourth method is off-site treatment and disposal of the wastewater. This fourth option is the most expensive as transportation costs and disposal costs may be enormous.
As previously noted, all four of the primary methods for handling the wastewater require a means/apparatus to store or otherwise contain the wastewater for some period of time. Because hydraulic fracturing may produce upwards of 5,000 barrels of wastewater per day per well, the storage capacity must be large and readily available during the fracking operation.
The huge volume of water that must be available and handled/processed during fracking operations, many of which occur in arid and semiarid areas, is another significant burden that must be addressed.
Enormous volumes of fresh water/sweet water must be available and easily accessible at all times.
Fresh water supplies must be kept separate from waste water storage to prevent contamination of the fresh water.
Evaporation loss must be minimized/eliminated.
Open access to the waste water, such as in a settling pond, creates risks to the environment and wildlife which may try to drink the contaminated waste water.
In geographic areas that experience low temperatures, open ponds may freeze reducing the quantity of available fluidic water for operations unless the water is heated.
Steel wall and/or concrete tanks may contain the water and reduce/eliminate open access and evaporation, but are expensive to construct and are generally permanent and therefore are not re-usable.
Water retaining pits may be excavated and thereafter lined with a liner or similar fluid impermeable barrier, but such pits are hazardous, expensive to construct, create plumbing complexities and are difficult to monitor for leakage. Further such pits must typically be “filled in” after the fracking operation is completed which further increases costs and may lead to environmental scarring.
Space is at a premium on fracking sites and therefore use of large amounts of surface area for water storage reduces space required for essential equipment and supplies.
Flexible storage tanks, or “pillow tanks” such as those described in U.S. Pat. No. 7,213,970 to Reicin, et al. issued May 8, 2007 are known, but heretofore such fluid storage tanks have not been used in the fracking industry. Such fluid storage tanks are commonly used by the United States military to store aviation fuels, potable water, waste water and the like at remote locations where it is impractical to erect permanent fluid storage tanks. Such fluid storage tanks are preferable to the military because of their transportability, reusability, ease of set up and small size when not filled with fluid. However, the United States Government also benefits from the legal doctrine of sovereign immunity and is therefore generally immune from liability if such tanks rupture, burst or leak their contents onto the ground causing pollution/contamination. Fracking operators are not entitled to such immunity and therefore use of such flexible storage tanks for containment of wastewater is an endeavor that is “fraught” with significant risk. This is especially true when numerous large vehicles may be moving on and about the drill site which is often small and contained and filled with hazardous moving machinery and equipment.
What is needed is a reusable erectable fluid storage containment structure that is configurable to be erected in oddly shaped areas of a fracking site to contain fresh water and to contain waste water while protecting the workers, the environment, wildlife and the fracking operation. The containment must have a primary containment and a secondary containment for safety redundancy and be secure, stable, safe and transportable and is reusable for use at site after site.
Our invention overcomes these difficulties and minimizes the risks by providing a removable reusable structure that surrounds, supports and protects a flexible fluid storage vessel, the structure containing a secondary containment for safety redundancy and the structure providing lateral and vertical support for the flexible fluid storage vessel and for the secondary containment to “contain” the vessel at a specific location at a fracking site which may need to be located, due to space restrictions, in an area having a configuration that is not suitable for known fluid storage.
Our invention resolves various of these aforementioned problems by providing an apparatus for large capacity fluid storage vessels to be erected on site to store fresh water for, as well as to store waste water from, hydro-fracking operations.
Some or all of the problems, difficulties and drawbacks identified above, and other problems, difficulties, and drawbacks may be helped or solved by the inventions shown and described herein. Our invention may also be used to address other problems, difficulties, and drawbacks not set out above or which are only understood or appreciated at a later time. The future may also bring to light currently unknown or unrecognized benefits which may be appreciated, or more fully appreciated, in the future associated with the novel inventions shown and described herein.